In the prosperous countries, roughly 20%, or one in five will die of cancer. The most frequently occurring cancers worldwide in descending order are: stomach, lung, breast, colon/rectum, cervix and mouth/pharynx. The cytolytic activity of most available anti-tumor chemicals is due to the inhibition of the synthesis and replication of DNA in tumor cells. Surgery, chemotherapy and radiation show limited success, and furthermore, these procedures remove or destroy normal cells along with cancer cells. Therefore, it is of interest to search for new anti-cancer agents having a different mode and site of activity. Moreover, cancer therapy using toxic chemicals give serious adverse side effects and other unpleasant results such as Alopecia (hair loss) which is one of the most distressing one among others.
The search for specific treatments has been vigorously pursued for over a half century, and the use of chemicals to treat cancer continues. The treatment of cancer needs to be changed from chemotherapy to biotherapy using biologicals at much lower dose levels. Monoclonal antibodies alone or coupled with ricin and interferons are the only biologicals until now used for cancer therapy.
Snake venom is a complex mixture of many substances such as toxins, enzymes, growth factors, activators and inhibitors, with wide spectrum of biological activities. For a long time it is believed that snake venom proteins have potential for the treatment of cancer, viral diseases, epilepsy and neurological disorders such as Alzheimer's and Parkinson's diseases etc. A book from CRC press by Kurt F. Stocker entitled "Medical Use of Snake Venom Proteins" reveals the state of the art. Tu and Giltner reported that venoms from the snake families Elapidae, Viperidae and Crotalidae, but not Hydrophidae, caused lysis of Yoshida sarcoma and KB cells. Chaim-Matyas and Ovadia studied the cytotoxic activity of various snake venoms in vitro and in-vivo, using melanoma and chondrosarcoma cells. Braganca et al. were probably first to isolate a factor from cobra venom which is selectively cytotoxic to cancer cells. Subsequently, these investigators isolated the cytotoxic factor having a molecular weight of 10,500 daltons. As recently as 1985, Iwaguchi et al. studied the cytotoxic activity of a cytotoxin isolated from Indian cobra venom against experimental Yoshida tumor cells and observed that the cytolytic activity on tumor cells was far stronger than on exudate cells such as: spleen cells and erythrocytes from rat. Besides, crude snake venoms, purified snake venom proteins have also been reported to have cytolytic activity on KB and Yoshida tumor cells.
Currently, numerous chemicals are being used to treat various types of cancers and such treatment is termed chemotherapy. Chemotherapy is associated with adverse side effects, such as hair loss, diarrhea skin rash, etc., simply because the chemicals used to kill cancer cells also affect normal cells adversely. Chemotherapy requires different chemicals for different types of cancers. The cancer treatment should be changed from chemotherapy to biotherapy using biologicals. Monoclonal antibodies coupled with ricin or other toxins are currently the only biologicals considered for cancer therapy. We strongly believe that snake venom derived Atroporin and Kaotree can play such a biological role by specifically targeting cancer cells.